1. Field of the Invention
The present invention relates, in general, to a side-emitting light-emitting diode (LED) lens that is configured such that the overall volume thereof can be reduced, and a backlight unit (BLU) and display device having the same.
2. Description of the Related Art
Generally, liquid crystal displays (LCDs) are provided in display devices that are used for computer monitors, TVs, or the like. Such LCDs require a separate light source since they do not generate light themselves.
As light sources for LCDs, several fluorescent lamps, such as a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL), or a plurality of light-emitting diodes (LEDs) are used. Light sources are provided on a backlight unit (BLU) together with a light guide plate (LGP), a plurality of optical sheets, a reflector plate, and the like.
Recently, from among these light sources, LEDs are attracting interest as a next-generation light source since they consume less power, have superior endurance, and can reduce manufacturing costs. However, when LEDs are used as a light source, light tends to be emitted while being confined to a restricted area. Therefore, in order to apply LEDs to a planar light source, such as a display device, it is required to make the light be uniformly distributed over a wider area.
Therefore, recently, LED lenses that perform such a function are under active study. A “SIDE-EMITTING LED LENS” was disclosed in U.S. Pat. No. 6,679,621. However, this invention has problems related to difficulties in its fabrication.
A “SIDE-EMITTING LED AND LENS ADAPTED THERETO” was disclosed in Korean Patent No. 10-0639873. FIG. 1 is a view showing the lens of the related art.
As shown in FIG. 1, the lens 1 has an incident surface, a top surface 2, and a side surface 3. The incident surface includes a convex surface 4, incident surfaces 5 and lower total reflection surfaces 6. The incident surfaces 5 and the lower total reflection surfaces 6 are connected to and alternate with each other.
With this configuration, a ray of light generated by an LED 7 enters through the convex surface 4 of the incident surface and then is incident on the top surface 2, in a substantially vertical direction, through the convex surface 4. In contrast, another ray of light generated by the LED 7 enters through one incident surface 5 and is reflected from the lower total reflection surfaces 6 before being incident on the top surface 2 in a substantially vertical direction. In addition, the light that has struck the top surface 2, in a substantially vertical direction, is totally reflected from the top surface 2 so as to be emitted to the outside through the side surface 3.
However, as in the lens 1, the top surface 2 must be steeply inclined upward in order to totally reflect the light that is incident on it in a substantially vertical direction. This significantly increases the overall height of the lens 1, as well as the overall volume of the lens 1, which can be problematic. In addition, when the overall volume of the lens 1 is increased as such, the material costs for manufacture of the lens 1 are also increased, thereby increasing the overall manufacturing costs of the lens.
The foregoing is intended merely to aid in the understanding of the background of the present invention, and is not intended to mean that the present invention falls within the purview of the related art that is already known.